Weird how territorial people get about being told when a relation is pregnant. It's almost like when your pregnant you become communal property. There's a weird dubbing war and hierarchy.
Speaking as someone that had a late loss, I wouldn't be eager to share the news because I wouldn't want my DSC to get excited and watch her heart break again. That's my family and set up on what suits our family best. That rule won't apply to all.
Re DH parents - that's really up to him. It's a choice you make as a couple and it's not for one to dictate to another how soon parents in law are told. If he doesn't want to say to them I wouldn't force it and if he wants to tell them I would support that too.
Having seen both sides of the coin, not all pregnancies have happy outcomes and you get to decide as a couple who is told as a result.
Before anyone @ me - I had to deal with SDD sobbing and spend a large percentage of time managing her OCD brought on by stress because she felt that she had cause the baby to die because she had thoughts that werent positive (aka she didn't want to share me and was worried about what a baby would mean- we are v close) she didn't have anything outside completely normal thoughts and I have told her this along with supported re counselling.
You know your family, you know best. No one has the right to dictate how or when you share the news.
Having said that it's always nice to share the news before it becomes obvious so they don't feel left out ect.